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Two-dimensional orthoglide mechanism for revealing areflexive human arm mechanical properties

Höppner, Hannes and Grebenstein, Markus and Smagt van der, Patrick (2015) Two-dimensional orthoglide mechanism for revealing areflexive human arm mechanical properties. In: IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pp. 1178-1185. 2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 28 Sept - 02 Oct 2015, Hamburg, Deutschalnd.

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Abstract

The most accurate and dependable approach to the in-vivo identification of human limb stiffness is by position perturbation. Moving the limb over a small distance and measuring the effective force gives, when states are steady, direct information about said stiffness. However, existing manipulandi are comparatively slow and/or not very stiff, such that a lumped stiffness is measured. This lumped stiffness includes the limb response during or after reflexes influenced by both, the passive musculotendon and active neuronal component. As this approach usually leads to inconsistencies between the data and the stiffness model, we argue in favour of fast, pre-reflex impedance measurements---i.e., completing the perturbation movement and collecting the data before effects of spinal reflexes or even from the motor cortex can influence the measurements. To obtain such fast planar movements, we constructed a dedicated orthoglide robot while focusing on a lightweight and stiff design. Our subject study of a force task with this device lead to very clean data with always positive definite Cartesian stiffness matrices. By representing them as ellipses, we found them to be substantially bigger in comparison to standard literature which we address to a larger number of recruited motor units. While ellipses orientation and the length of their main axis increased, the shape decreased with the exerted force. The device will be used to derive design criteria for variable-stiffness robots, and to investigate the relation between muscular activity and areflexive joint stiffness for tele-operational approaches.

Item URL in elib:https://elib.dlr.de/98564/
Document Type:Conference or Workshop Item (Speech)
Title:Two-dimensional orthoglide mechanism for revealing areflexive human arm mechanical properties
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Höppner, Hanneshannes.hoeppner (at) dlr.deUNSPECIFIED
Grebenstein, MarkusMarkus.Grebenstein (at) dlr.deUNSPECIFIED
Smagt van der, PatrickTechnische Universität MünchenUNSPECIFIED
Date:1 October 2015
Journal or Publication Title:IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:Yes
Page Range:pp. 1178-1185
Status:Published
Keywords:Human Impedance Measurements, Variable Stiffness Robotics, Manipulandum Design
Event Title:2015 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS)
Event Location:Hamburg, Deutschalnd
Event Type:international Conference
Event Dates:28 Sept - 02 Oct 2015
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Technology
DLR - Research area:Raumfahrt
DLR - Program:R SY - Technik für Raumfahrtsysteme
DLR - Research theme (Project):R - Vorhaben Terrestrische Assistenz-Robotik
Location: Oberpfaffenhofen
Institutes and Institutions:Institute of Robotics and Mechatronics (since 2013) > Mechatronic Components and Systems
Deposited By: Höppner, Hannes
Deposited On:15 Oct 2015 20:11
Last Modified:31 Jul 2019 19:55

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